Before the first soldier crossed the border, the Sicherheitsdienst had already printed a book. The Sonderfahndungsbuch Polen — the Special Prosecution Book Poland — listed more than 61,000 Polish citizens by name and birthdate. Politicians, scholars, actors, doctors, lawyers, priests, military officers, members of the nobility. The list had been assembled with help from the German minority living inside the Second Polish Republic. The point of the list was murder. The first Einsatzgruppen — mobile killing squads of the SS — followed the Wehrmacht into Poland with copies. Between the autumn of 1939 and the spring of 1940, in an operation called Intelligenzaktion, German forces shot roughly 60,000 members of the Polish leadership class, region by region, neighborhood by neighborhood. The point was to decapitate Polish society so it could not resist what was coming next.

In the spring of 1940 the Generalgouvernement under Hans Frank launched the Ausserordentliche Befriedungsaktion — the Extraordinary Pacification Operation, known to history as the AB-Aktion. Roughly 30,000 Poles deemed dangerous to German rule were arrested. About 7,000 were executed. In the Palmiry forest north of Warsaw, between December 1939 and July 1941, German firing squads shot roughly 1,700 Polish prisoners in secret nighttime executions and buried them in mass graves dug in advance. Among the dead at Palmiry were the Polish Olympic gold medalist Janusz Kusocinski, the writer Stefan Kopec, the Speaker of the Sejm Maciej Rataj, and the Boy Scout commander Witold Hulewicz. The graves were marked only after the war. Today birch trees grow between rows of low stone crosses in the Kampinos forest, each cross with a name where a name was knowable.

Of the roughly 3.3 million Jews living in Poland in 1939, fewer than 300,000 were alive in 1945. The largest single concentration was crowded into the Warsaw Ghetto, where 400,000 people were sealed behind a wall less than a square mile in area — a density of 7.2 people per room. The Lodz Ghetto held a further 160,000. Beginning in the summer of 1942, the deportations to the killing centres began: Treblinka, Sobibor, Belzec, Chelmno, and the gas chambers at Auschwitz-Birkenau. From the Warsaw Ghetto alone, 254,000 people were sent to Treblinka in two months. Industrial murder operated on factory schedules. The Operation Reinhard camps killed roughly 1.7 million Polish Jews in eighteen months. When the Warsaw Ghetto rose in armed revolt in April 1943, knowing the deportations meant certain death, the resistance held SS troops off for nearly a month before the ghetto was burned to the ground.

On the first of August 1944, with Soviet forces a few miles east of the Vistula, the Polish Home Army rose against the Germans in Warsaw. They held parts of the city for sixty-three days. The Soviets stopped on the eastern bank and watched. When the rising failed in early October, Hitler ordered Warsaw razed as collective punishment. Special demolition units — Verbrennungs- und Vernichtungskommandos, burning and destruction commandos — went block by block through the surrendered city with flamethrowers and explosives. The Royal Castle, the National Library, the Old Town, the entire historic core were dynamited. By January 1945 roughly 85 percent of the buildings on the left bank of the Vistula were rubble. Around 200,000 civilians had died during the rising itself. The destruction of Warsaw was not a battle. It was the deliberate erasure of a city as a political statement.

The numbers compiled by Poland's Institute of National Remembrance: 2.7 to 3 million Polish Jews murdered, 1.8 to 2.77 million ethnic Poles killed. About 200,000 Polish children kidnapped for forced Germanisation. Roughly 1.5 million Poles deported as forced labourers to the Reich. The Polish intelligentsia — the lawyers, professors, priests, officers, journalists, the people who would have rebuilt the country — was deliberately and very nearly successfully exterminated. What survived survived in fragments. The diary of the teenage Dawid Sierakowiak from the Lodz Ghetto. The buried photographs of Henryk Ross. The Oneg Shabbat archive that Emanuel Ringelblum's circle hid in milk cans under the rubble of the Warsaw Ghetto and that postwar workers dug back out. These records exist because the people who kept them understood, with absolute clarity, that they were being murdered and that someone needed to know.